I. Field of the Invention
The present invention relates to a battery charging system for an aircraft having an alternator.
II. Description of Related Art
Most power driven general aviation aircraft have only one engine. Reliable electric power, however, is vital to the proper operation of the aircraft. Such electrical power is necessary not only to operate many of the controls of the aircraft, but also to communicate with Air Traffic Control, obtain in flight weather information, detect other airborne aircraft, as well as monitor and maintain engine operating conditions.
In most propeller driven general aviation aircraft, the engine motor rotatably drives a field coil of an alternator. A stator coil surrounds the field coil and provides the alternating current output from the alternator. This alternating current, however, is then rectified into DC current which is then used to charge the battery which in turn provides electrical power for the aircraft.
In order to control the output voltage from the alternator, a current is supplied through the field winding wherein the magnitude of the field current in turn varies the DC output voltage from the alternator. In order to control this current, typically a voltage regulator is electrically connected in series between the power supply and one end of the field coil. The other end of the field coil is, in turn, grounded.
Due to both weight and room considerations, most general aviation aircraft do not include redundant batteries or redundant alternators. As such, failure of the electrical system, and the battery charging system, occasionally occurs. Such failures render the aircraft difficult or even impossible to aviate.
Most electrical failures of such aircraft result from one of the following five causes:
1. A defective voltage regulator;
2. An open or broken field winding;
3. A short circuit of the alternator field winding;
4. A defective brush for the alternator field coil; or
5. A defective alternator field winding.